1. Field of the Invention
The present invention relates to devices and methods used to test the compressibility of sporting balls, such as tennis balls, racquet balls and the like. More specifically, the present invention relates to a portable handheld device that can be used by a player to determine the condition of a ball prior to the start of the game.
2. Description of the Prior Art
Under the rules of the American Tennis Association, tennis balls are manufactured to specific tolerances, thereby reducing the role of the ball as a variable during play. Specifically, a tennis ball should have a forward deformation between 0.22 inches and 0.29 inches and a return deformation of between 0.35 inches and 0.425 inches when experiencing an eighteen pound load. During manufacture, tennis balls are typically tested in large complex machines such as the Stevens deflectometer, invented by Percy Stevens and patented in Great Britain under Patent No. 230,250. Other such complex testing machines are exemplified by U.S. Pat. No. 4,876,658 to Hass, entitled METHOD AND APPARATUS FOR SYSTEMATICALLY TESTING OBJECTS INCLUDING TENNIS BALLS, which is assigned to the United States Tennis Association.
The use of such complex machines during manufacture does ensure that most tennis balls purchased by players meet the proper design specifications. However, as every player knows, tennis balls do not last forever. As a tennis ball is repeatedly struck, the ball deforms. After a while, the cycles of deformation permanently effect the ball, causing the tennis ball to become soft. The softening of the tennis ball is progressive. As a result, it is common that a ball may become too soft after only a few games. As the ball falls below accepted tolerances, play is effected because the ball does not bounce as high as would be expected or rebound off the tennis racket as quickly as would be expected. A need therefore exists for a means that would enable a player to test the "softness" of a ball before or between games in a match, thereby eliminating any defective ball before the ball adversely effects the play of the game.
In the prior art, there have been several devices invented that are intended to test the softness of a tennis ball. Such prior art devices are exemplified by U.S. Pat. No. 5,291,774 to Putnam, entitled TENNIS BALL TESTER and U.S. Pat. No. 5,222,391 to Reenstra also entitled TENNIS BALL TESTER. However, both of these prior art references have undesirable features. The Putnam device is large and bulky and is unlikely to be carried in a player's tennis bag. The Reenstra device is electric and uses an electronic pressure sensor and control circuitry that adds greatly to the cost and complexity of the device.
It is therefore an object of the present invention to provide a tennis ball testing device that is inexpensive, light weight, easy to use and rapid to use.
It is a further object of the present invention to provide a method of testing a tennis ball that is inexpensive to execute and rapid to perform.
These objects are fulfilled by the present invention as described and claimed below.